A pot culture study was conducted during February, 2014 to evaluate the effect of organic manure, PSB or lime on Udaipur Rock Phosphate (URP) dissolution, P and Ca availability and biomass yield of hybrid napier grass in three different acid soils (Typic Halpludalf) in Odisha, India. The experiment was conducted in a completely randomized design (CRD) with three replications and 18 treatments consists of 3 low pH soils - S1 (), S2 (), S3 () and six rock phosphate treatments - T1-Control, T2-200%P through URP, T3-50%P through URP+50%P through SSP, T4- 100%P through URP +FYM @5 tha-1 , T5-100%P through URP +PSB @ 10 kg ha-1 and T6-100% P through URP + lime @ LR (Lime Requirement). The URP namely sourced from FCI Aravali Gypsum and Minerals India Limited (FAGMIL), Jodhpur contains total P, Ca, Mg and K indicating a moderate reactive material. Application of URP alone or with amendments increased soil pH significantly, attained its peak at 4th cutting and then decreased gradually, but remained above the initial value at the end of 8th cutting. Among the treatments, URP + lime (T6) recorded highest pH value followed by 200% URP(T2) and URP + SSP(T3) in all soils. | Relative efficiency of udaipur rock phosphate combined with amendments in acid soils of Odisha, India
